The invention relates to a rotary step motor provided with unipolar control. Step motors are used, for example, in clocks or other timekeeping devices and are usually controlled by signals of alternating polarity which flow through a control coil wound about the stator. The resulting magnetic field produces alternating north and south poles periodically in response to the alternating energization. A polarized rotor positioned within the alternating magnetic field is caused to rotate, and the direction of rotation is established by mechanical devices or by a specific shaping of the pole tips of the stator. Rotary step motors of the kind just described, operating in response to signals of alternating polarity, are known as bipolar motors. Their disadvantage is that they require the use of electronic driving circuits of a rather complex nature in order to produce current pulses of alternatingly opposite polarities.